1. Prior Art
U.S. Pat. No. 4,343,495 entitled "Conductor Tieback Connector" of Nobileau and Jones.
2. Field of Invention
This invention relates to offshore subsea well apparatus and in particular to a connector for connecting a tieback conductor to a wellhead located subsea. More specifically, this invention is an improvement over the tieback connector of the foregoing patent in that the tieback connector of this invention will connect to a wellhead located subsea having internal grooves, often referred to as running tool grooves, on the bore of the wellhead or other tubular member such as a mudline system.
The foregoing patent explained in detail the need for running of tieback conductors from a platform deck to a subsea wellhead. The tubular connector of the foregoing patent utilized a tapered guide (funnel) for initial stabbing and bearing surfaces which operated on the outside surface of the wellhead to force the conductor string into angular alignment with the wellhead under the influence under the weight of the conductor string. Seals located between the tieback connector and the wellhead were compressed with axial movement of the tieback connector and thereafter a lock-down bushing engaged internal running tool threads on the wellhead and clamped the wellhead without the rotation of the conductor.
Such a tieback connector solved angular misalignment problems between the conductor and the wellhead when the conductor approached the wellhead and solved the problem of damage to the seals by the elimination of conductor rotation for makeup.
The tieback connector of the foregoing patent with its lock-down bushing, therein also referred to as a floating bushing, required threads on the internal bore of the wellhead for makeup but with the advent of running tool grooves on the internal bore of the wellhead (in lieu of threads) the patented tieback connector was no longer compatible. Thus, there is a need for a tieback connector capable of function with wellheads having internal running tool grooves yet incorporating all of the other advantages of the patented tieback connector.
In connection with running tool grooves on the copending wellhead, reference is also made to the U.S. Pat. Application of Calder and Cromar, Ser. No. 466,236, filed Feb. 14, 1983 entitled "Conductor Tieback Connector" which also discloses locking dogs engagable in such grooves but in a totally different type of connector.